Organic light emitting diode (OLED) devices are an emerging technology for display applications, and are only now advancing to dimensions exceeding those found in such common devices as cell phones. As such, they are still expensive to produce. Typically, OLED displays incorporate diodes that emit at different wavelengths (colors). One approach for reducing manufacturing costs is to produce a display that emits at a single color (white), and using color filters to express the colors needed to produce a full color display, similar to the approach taken for the more mature liquid crystal display technologies. Alternatively, color filters may be used with color producing OLEDs (e.g. RGB output) to adjust the colors emitted by the display.
One difficulty associated with OLED devices, such as OLED-based displays, is the need to maintain a hermetically sealed environment for the organic light emitting materials used for the OLEDs. This arises because the organic materials quickly degrade in the presence of even minute amounts of oxygen or moisture. To that end, a glass seal may be provided by a glass-based frit material that seals two glass plates together, provides sufficient hermeticity to the organic materials contained within the resulting package. Such glass packages have proven to be far superior to adhesive-sealed devices. In a typical frit sealed configuration, the glass-based frit is deposited on a first glass plate, referred to as the cover plate, in the form of a closed loop. The frit is deposited as a paste that is subsequently heated in a furnace for a period of time and at a temperature sufficient to at least partially sinter (pre-sinter) the frit in place on the cover plate, making later assembly of the display easier. The OLED is then deposited on a second glass plate, generally referred to as the backplane plate or simply backplane. The OLED may contain, for example, electrode materials, organic light emitting materials, hole injection layers, and other constituent parts as necessary. Generally, the two plates are then brought into alignment and the pre-sintered frit is heated with a laser that softens the frit and forms a hermetic seal between the two glass plates.
OLED display devices that incorporate a color filter may include the color filter on the cover plate, thereby making the process described above impractical, as the high furnace temperature applied to the cover and frit during the pre-sintering portion of the process is likely to destroy the color filter elements.